Dabco catalyzed synthesis of new 2-amino-8-arylidene-4-aryl-5,6,7,8- tetrahydrobenzo-4H-pyran-3-carbonitriles from α,α- BIS(substituted benzylidene)cycloalkanones

Article abstract of DOI:10.4314/bcse.v26i2.8

The synthesis of new series of 2-amino-8-arylidene-4-aryl-5,6,7,8- tetrahydrobenzo-4H-pyran-3- carbonitriles from the reaction of α,α-bis(substituted benzylidene)cycloalkanones with malononitrile under reflux conditions in the presence DABCO in good to ex

Full text of DOI:10.4314/bcse.v26i2.8

Bull. Chem. Soc. Ethiop. 2012, 26(2), 249-255.
Printed in Ethiopia
DOI: http://dx.doi.org/10.4314/bcse.v26i2.8
ISSN 1011-3924
 2012 Chemical Society of Ethiopia
DABCO CATALYZED SYNTHESIS OF NEW 2-AMINO-8-ARYLIDENE-4-ARYL-
5,6,7,8-TETRAHYDROBENZO-4H-PYRAN-3-CARBONITRILES FROM α,ά-
BIS(SUBSTITUTED BENZYLIDENE)CYCLOALKANONES
Gholam Hossein Mahdavinia1*, Mohammad Ali Bigdeli2 and Fatemeh Kooti2
1Department of Chemistry, Marvdasht Branch, Islamic Azad University, Marvdasht, Iran
2Faculty of Chemistry, Tarbiat Moallem University, 49 Mofateh St., Tehran, Iran
(Received June 2, 2011; revised January 10, 2012)
ABSTRACT. The synthesis of new series of 2-amino-8-arylidene-4-aryl-5,6,7,8-tetrahydrobenzo-4H-pyran-3-
carbonitriles from the reaction of α,ά-bis(substituted benzylidene)cycloalkanones with malononitrile under reflux
conditions in the presence DABCO in good to excellent yields has been described.
KEY WORDS: DABCO, 4H-Pyran, α,ά-bis(substituted benzylidene)cycloalkanone
INTRODUCTION
4H-pyran and its derivatives are important class of organic and bioorganic compounds. They are
often used in cosmetics, pigments and are utilized as potentially biodegradable agrochemicals
[1, 2]. A number of compounds containing 4H-pyrane moiety have been used in wide range of
therapeutic areas [3-5]. Polyfunctionalized 4H-pyrans constitute a structural unit of a number of
biologically interesting compounds which possess various pharmacological activities, such as
antiallergic [5], antitumor [6] and antibacterial [7-8]. 4H-Pyran derivatives are also potential
calcium channel antagonists [9] which are structurally similar to biologically active 1,4-
dihydropyridines. In addition, 2-amino-4H-benzo[b]pyrans are used in the synthesis of
difficultly accessible annulated heterocyclic [10].
Ar
O
CN
CN
Z
DABCO
H2C
+
Ar
Ar
CN
O
NH2
Reflux, EtOH
Z
Ar
H
Z=CH2 , CH(Me)
1
2
3
Scheme 1. Synthesis
carbonitrile.
of
2-amino-8-arylidene-4-aryl-5,6,7,8-tetrahydrobenzo-4H-pyran-3-
The 4H-pyrans are synthesized mainly by a three-component coupling reaction of aromatic
aldehydes and malononitrile with ketones or β-diketones by bases catalysts or acid catalysts.
Many of the methods reported for the synthesis of these compounds in the literature [11-28].
Recently synthesis and biological properties of the new series of this compound entitled 2-
amino-8-arylidene-4-aryl-5,6,7,8-tetrahydrobenzo-4H-pyran-3-carbonitriles have been attracted
__________
*Corresponding author. E-mail: hmahdavinia@gmail.com

250
Gholam Hossein Mahdavinia et al.
for chemist [29-31]. For the mentioned reasons and as part of our study on the development of
new routes to the synthesis of heterocyclic system [32], in this paper, we report the synthesis of
some new 2-amino-8-arylidene-4-aryl-5,6,7,8-tetrahydrobenzo-4H-pyran-3-carbonitrile from
α,ά-bis(substituted benzylidene)cycloalkanones and malononitrile in ethanol in the presence of
DABCO under reflux conditions (Scheme 1).
EXPERIMENTAL
Chemicals were purchased from Fluka and Merck. Melting points were determined using an
Electrothermal 9100 and are not corrected for known compounds. Thin layer chromatography
(TLC), on commercial aluminum-backed plates of silica gel 60PF254, was used to monitor the
1
progress of the reactions. H NMR and 13C NMR spectra were recorded on a Bruker Avance-
300 MHz spectrometer in the presence of TMS as internal standard. IR spectra were recorded
using a Perkin-Elmer 843 spectrometer using KBr discs.
General procedure for 2-amino-3-cyano-4H-pyran derivatives
A mixture of the bisarylidenecyclohexanone 1 (1 mmol), malononitrile 2 (1 mmol), and
DABCO (10 mol %) in ethanol (15 mL) was stirred at reflux condition for appropriate time
according to Table 1. After completion of the reaction, the mixture was kept at room
temperature and the resulting crystalline product was collected by filtration and it was washed
with cold ethanol. The product was found to be pure and no further purification was necessary.
Table 1. Synthesis of 2-amino-8-arylidene-4-aryl-5,6,7,8-tetrahydrobenzo-4H-pyran-3-carbonitrile.
M.p. (0 C)
Product
Ar
Z
Time (min) Yielda (%)
Found
Reported
3a
3b
3c
3d
3e
3f
C6H5
4-MeC6H4
4-ClC6H4
2-ClC6H4
4-MeOC6H4
4-FC6H5
4-BrC6H4
C6H5
CH2
CH2
5
95
90
95
90
80
95
90
80
80
80
85
90
90
80
232-234 230-231 [29]
165-166 161-162 [29]
220-221 215-216 [29]
238-240 237-238 [29]
15
20
10
15
20
20
15
20
25
15
20
25
15
CH2
CH2
CH2
221-223
227-230
219-221
205-208
218-221
200-203
201-204
207-209
137-140
230-232
------
------
------
------
------
------
------
------
------
------
CH2
3g
3h
3i
CH2
CH(Me)
4-MeC6H4 CH(Me)
4-MeOC6H4 CH(Me)
3j
3k
3l
4-ClC6H4
4-FC6H4
2-ClC6H4
4-BrC6H4
CH(Me)
CH(Me)
CH(Me)
CH(Me)
3m
3n
aIsolated yields.
2-Amino-8-[4-methoxybenzylidene]-4-(4-methoxylphenyl)-5,6,7,8-tetrahydrobenzo-4H-pyran-3-
carbonitrile. IR (KBr): vmax = 3477, 3377, 2196, 1673, 1640, 1609, 1515, 1412, 1255 cm-1.
Anal. calcd (%) for C25H24N2O3: C, 75.01; H, 6.01; N, 7.01; found: C, 74.26; H, 6.04; N, 6.90.
1H NMR (300 MHz, CDCl3): δ = 1.54-2.05 (m, 4H, 2 CH2), 2.53-2.76 (m, 2H, CH2), 3.80 (s,
3H, MeO), 3.83 (s, 3H, MeO), 3.92 (s, 1H, CH), 4.48 (s, 2H, NH2), 6.81 (s, 1H, CH=C), 6.85-
7.28 (m, 8H, 2 C6H4). 13C NMR (75 MHz, CDCl3): δ = 22.3, 27.1, 27.4, 42.7, 55.3, 60.8, 113.6,
114.1, 114.7, 122.0, 127.9, 128.9, 129.5, 130.5, 135.1, 141.4, 145.0, 158.4, 158.7, 158.8. MS
(EI, 70 eV): m/z = 400.22 [M+].
Bull. Chem. Soc. Ethiop. 2012, 26(2)

New 2-amino-8-arylidene-4-aryl-5,6,7,8-tetrahydrobenzo-4h-pyran-3-carbonitriles
251
2-Amino-8-[4-fluorobenzylidene]-4-(4-fluorophenyl)-5,6,7,8-tetrahydrobenzo-4H-pyran-3-
carbonitrile (3e). IR (KBr): vmax = 3470, 3329, 2198, 1674, 1645, 1506, 1416, 1224 cm-1. Anal.
1
calcd (%) for C23H18F2N2O: C, 73.40; H, 4.78; N, 7.45; found: C, 73.31; H, 4.72; N, 7.45. H
NMR (300 MHz, CDCl3): δ = 1.54-1.70 (m, 2H, CH2), 1.87-2.06 (m, 2H, CH2), 2.50-2.73 (m,
2H, CH2), 3.96 (s, 1H, CH), 4.56 (s, 2H, NH2), 6.83 (s, 1H, CH=C), 7.00-7.28 (m, 8H, 2 C6H4).
13C NMR (75 MHz, CDCl3): δ = 22.1, 26.9, 27.3, 42.8, 60.4, 115.0, 115.3, 115.5, 121.7, 129.1,
129.3, 129.4, 130.7, 138.6, 141.8, 158.7, 158.8, 163.4, 163.7.
2-Amino-8-[4-bromobenzylidene]-4-(4-bromophenyl)-5,6,7,8-tetrahydrobenzo-4H-pyran-3-
carbonitrile (3f). IR (KBr): vmax = 3448, 3331, 2197, 1667, 1637, 1599, 1486, 1419 cm-1. Anal.
1
calcd (%) for C23H18 Br2N2O: C, 55.42; H, 3.61; N, 5.62; found: C, 55.17; H, 3.31; N,5.62. H
NMR (300 MHz, CDCl3): δ = 1.60-1.68 (m, 2H, CH2), 1.86-2.04 (m, 2H, CH2), 2.51-2.70 (m,
2H, CH2), 3.94 (s, 1H, CH), 4.56 (s, 2H, NH2), 6.79 (s, 1H, CH=C), 7.11-7.49 (m, 8H, 2 C6H4).
13C NMR (75 MHz, CDCl3): δ = 22.1, 27.0, 27.4, 43.1, 60.0, 115.2, 119.7, 120.8, 121.3, 121.7,
129.6, 129.8, 130.8, 131.4, 131.9, 135.7, 141.5, 141.8, 158.8.
2-Amino-8-benzylidene-6-methyl-4-phenyl-5,6,7,8-tetrahydrobenzo-4H-pyran-3-carbonitrile
(3g). IR (KBr): vmax = 3431, 3338, 2185, 1666, 1639, 1619, 1591, 1412 cm-1. Anal. calcd (%)
for C24H20N2O: C, 81.81; H, 6.01; N, 7.95; found: C, 80.60; H, 6.24; N, 7.84. Major isomer-3h
1
(55%); H NMR (300 MHz, CDCl3): δ = 0.94 (d, J = 6.32 Hz, 3H, Me), 1.68-2.30 (m, 4H, 2
CH2), 2.87 (m, 1H, CH), 3.98 (s, 1H, CH), 4.52 (s, 2H, NH2), 6.93 (s, 1H, CH=C), 7.27-7.42
(m, 8H, 2 C6H4). 13C NMR (75 MHz, CDCl3): δ = 20.9, 28.9, 35.1, 36.1, 43.9, 60.6, 114.6,
120.0, 122.8, 126.8, 127.4, 127.8, 128.8, 129.2, 129.5, 137.0, 141.6, 143.0, 145.0, 158.8. Minor
isomer-3h (45%); 1H NMR (300 MHz, CDCl3): δ= 0.93 (d, J = 6.10 Hz, 3H, Me), 1.68-2.30 (m,
4H, 2 CH2), 2.90 (m, 1H, CH), 4.00 (s, 1H, CH), 4.56 (s, 2H, NH2), 6.93 (s, 1H, CH=C), 7.27-
7.42 (m, 8H, 2 C6H4). 13C NMR (75 MHz, CDCl3): δ= 20.9, 28.5, 34.7, 35.1, 43.1, 60.7, 114.5,
120.0, 122.7, 126.8, 127.4, 127.9, 128.7, 129.3, 129.5, 137.0, 141.2, 142.6, 145.0, 158.9.
2-Amino-8-[4-methylbenzylidene]-6-methyl-4-(4-methylphenyl)-5,6,7,8-tetrahydrobenzo-4H-
pyran-3-carbonitrile (3h). IR (KBr): vmax = 3455, 3324, 2203, 1676, 1647, 1602, 1514, 1414
cm-1. Anal. calcd (%) for C26H26N2O: C, 81.67; H, 6.81; N, 7.32; found: C, 81.40; H, 6.95; N,
1
7.28. Major isomer-3i (55%); H NMR (300 MHz, CDCl3): δ = 0.88 (d, J = 6.22 Hz, 3H, Me),
1.63-2.26 (m, 4H, 2 CH2), 3.35 (s, 3H, Me), 2.38 (s, 3H, Me), 2.84 (m, 1H, CH), 3.92 (s, 1H,
CH), 4.55 (s, 2H, NH2), 6.85 (s, 1H, CH=C), 7.10-7.40 (m, 8H, 2 C6H4); 13C NMR (75 MHz,
CDCl3): δ = 21.0, 21.1, 21.2, 28.9, 35.2, 36.0, 43.4, 60.5, 114.2, 120.0, 122.4, 127.8, 128.8,
129.1, 129.3, 133.8, 134.0, 136.5, 136.9, 139.6, 141.1, 158.9. Minor isomer-3i (45%); 1H NMR
(300 MHz, CDCl3): δ= 0.91 (d, J = 6.02 Hz, 3H, Me), 1.63-2.26 (m, 4H, 2 CH2), 3.34 (s, 3H,
Me), 2.37 (s, 3H, Me), 2.88 (m, 1H, CH), 3.90 (s, 1H, CH), 4.52 (s, 2H, NH2), 6.85 (s, 1H,
CH=C), 7.10-7.40 (m, 8H, 2 C6H4); 13C NMR (75 MHz, CDCl3): δ = 21.0, 21.1, 21.2, 28.5,
34.6, 35.1, 42.6, 60.6, 114.3, 120.1, 122.5, 127.7, 128.6, 129.2, 129.4, 133.8, 134.0, 136.5,
136.8, 140.1, 141.5, 158.9.
2-Amino-8-[4-methoxybenzylidene]-6-methyl-4-(4-methoxyphenyl)-5,6,7,8-tetrahydrobenzo-
4H-pyran-3-carbonitrile (3i). IR (KBr): vmax = 3420, 3328, 2196, 1676, 1647, 1604, 1511, 1417,
1252 cm-1. Anal. calcd (%) for C26H26N2O3: C, 75.36; H, 6.28; N, 6.76; found: C, 75.09; H,
1
6.29; N, 6.72. Major isomer-3j (56%); H NMR (300 MHz, CDCl3): δ = 0.88 (d, J = 6.24 Hz,
3H, Me), 1.61-2.25 (m, 4H, 2 CH2), 2.82 (m, 1H, CH), 3.80 (s, 3H, MeO), 3.83 (s, 3H, MeO),
3.91 (s, 1H, CH), 4.56 (s, 2H, NH2), 6.82 (s, 1H, CH=C), 6.84-7.29 (m, 8H, 2 C6H4), 13C NMR
(75 MHz, CDCl3): δ = 21.0, 28.9, 35.2, 36.0, 43.1, 55.1, 55.2, 60.6, 113.6, 113.7, 113.9, 120.1,
122.1, 127.8, 128.9, 129.5, 130.5, 134.9, 141.1, 158.4, 158.7, 158.9. Minor isomer-3j (44%);
Bull. Chem. Soc. Ethiop. 2012, 26(2)

252
Gholam Hossein Mahdavinia et al.
1H NMR (300 MHz, CDCl3): δ = 0.91 (d, J = 6.01 Hz, 3H, Me), 1.61-2.25 (m, 4H, 2 CH2), 2.87
(m, 1H, CH), 3.79 (s, 3H, MeO), 3.81 (s, 3H, MeO), 3.89 (s, 1H, CH), 4.53 (s, 2H, NH2), 6.81
(s, 1H, CH=C), 6.84-7.29 (m, 8H, 2 C6H4); 13C NMR (75 MHz, CDCl3): δ = 21.1, 28.5, 34.6,
35.9, 42.2, 55.1, 55.2, 60.7, 113.7, 114.0, 114.1, 120.1, 122.2, 128.0, 129.6, 130.0, 130.5,
135.3, 141.5, 158.4, 158.7, 158.9.
2-Amino-8-[4-chlorobenzylidene]-6-methyl-4-(4-chlorophenyl)-5,6,7,8-tetrahydrobenzo-4H-
pyran-3-carbonitrile (3j). IR (KBr): vmax = 3460, 3318, 2186, 1668, 1632, 1597, 1489, 1415,
1255 cm-1. Anal. calcd (%) for C24H20Cl2N2O: C, 68.08; H, 4.72; N, 6.62; found: C, 68.03; H,
1
4.52; N, 6.64. Major isomer-3k (54%); H NMR (300 MHz, CDCl3): δ= 0.88 (d, J = 6.25 Hz,
3H, Me), 1.58-2.24 (m, 4H, 2 CH2), 2.75 (m, 1H, CH), 3.94 (s, 1H, CH), 4.56 (s, 2H, NH2),
6.82 (s, 1H, CH=C), 7.15-7.34 (m, 8H, 2 C6H4), 13C NMR (75 MHz, CDCl3): δ = 20.8, 28.8,
35.1, 35.9, 43.4, 60.2, 114.3, 119.5, 121.8, 128.4, 129.0, 129.2, 129.8, 130.5, 132.7, 133.3,
135.3, 141.1, 141.5, 158.8. Minor isomer-3k (46%); 1H NMR (300 MHz, CDCl3): δ = 0.91 (d, J
= 6.03 Hz, 3H, Me), 1.58-2.24 (m, 4H, 2 CH2), 2.80 (m, 1H, CH), 3.92 (s, 1H, CH), 4.54 (s, 2H,
NH2), 6.82 (s, 1H, CH=C), 7.15-7.34 (m, 8H, 2 C6H4), 13C NMR (75 MHz, CDCl3): δ = 20.8,
28.5, 34.6, 35.0, 42.6, 60.3, 114.4, 119.5, 122.1, 128.4, 128.9, 129.2, 129.6, 130.5, 132.7,
133.2, 135.3, 141.2, 141.6, 158.9.
2-Amino-8-[4-fluorobenzylidene]-6-methyl-4-(4-fluorophenyl)-5,6,7,8-tetrahydrobenzo-4H-
pyran-3-carbonitrile (3k). IR (KBr): vmax = 3475, 3330, 2193, 1673, 1635, 1601, 1506, 1418
cm-1. Anal. calcd (%) for C24H20F2N2O: C, 73.84; H, 5.12; N, 7.18; found: C, 72.23; H, 5.85; N,
1
7.51. Major isomer-3l (56%); H NMR (300 MHz, CDCl3): δ= 0.88 (d, J = 6.23 Hz, 3H, Me),
1.61-2.24 (m, 4H, 2 CH2), 2.78 (m, 1H, CH), 3.94 (s, 1H, CH), 4.52 (s, 2H, NH2), 6.83 (s, 1H,
CH=C), 7.00-7.28 (m, 8H, 2 C6H4), 13C NMR (75 MHz, CDCl3): δ = 20.9, 28.5, 34.6, 35.9,
44.4, 60.6, 114.4, 115.4, 115.8, 119.7, 122.0, 129.1, 129.4, 130.8, 132.9, 138.7, 141.5, 158.8,
1
160.5, 163.7. Minor isomer-3l (44%); H NMR (300 MHz, CDCl3): δ = 0.91 (d, J = 6.01 Hz,
3H, Me), 1.61-2.24 (m, 4H, 2 CH2), 2.88 (m, 1H, CH), 3.95 (s, 1H, CH), 4.52 (s, 2H, NH2),
6.83 (s, 1H, CH=C), 7.00-7.28 (m, 8H, 2 C6H4), 13C NMR (75 MHz, CDCl3): δ = 20.9, 28.5,
34.6, 35.9, 44.4, 60.6, 114.3, 115.1, 115.6, 119.7, 121.8, 129.1, 129.5, 130.7, 132.9, 138.7,
141.4, 158.7, 160.0, 163.2.
2-Amino-8-[2-chlorobenzylidene]-6-methyl-4-(2-chlorophenyl)-5,6,7,8-tetrahydrobenzo-4H-
pyran-3-carbonitrile (3l). IR (KBr): vmax = 3444, 3327, 2195, 1677, 1605, 1470, 1413, 1254
cm-1. Anal. calcd (%) for C24H20Cl2N2O: C, 68.08; H, 4.72; N, 6.62; found: C, 68.02; H, 4.76;
1
N, 6.64. Major isomer-3m (56%); H NMR (300 MHz, CDCl3): δ = 0.88 (d, J = 6.23 Hz, 3H,
Me), 1.57-2.29 (m, 4H, 2 CH2), 2.64 (m, 1H, CH), 3.34 (s, 1H, CH), 4.57 (s, 2H, NH2), 6.86 (s,
1H, CH=C), 7.19-7.42 (m, 8H, 2 C6H4), 13C NMR (75 MHz, CDCl3): δ = 20.8, 28.4, 34.5, 35.1,
39.6, 59.2, 114.5, 119.5, 120.2, 127.6, 128.2, 128.5, 129.4, 129.7, 130.4, 130.5, 130.6, 135.2,
1
139.8, 140.7, 142.3, 145.5, 160.0. Minor isomer-3m (44%); H NMR (300 MHz, CDCl3): δ =
0.91 (d, J= 6.02 Hz, 3H, Me), 1.57-2.29 (m, 4H, 2 CH2), 2.70 (m, 1H, CH), 3.32 (s, 1H, CH),
4.55 (s, 2H, NH2), 6.86 (s, 1H, CH=C), 7.19-7.42 (m, 8H, 2 C6H4), 13C NMR (75MHz, CDCl3):
δ = 20.8, 28.7, 34.4, 35.0, 39.0, 59.3, 114.6, 119.5, 120.1, 127.5, 128.1, 128.3, 129.2, 129.6,
130.5, 130.4, 130.4, 135.4, 139.9, 140.5, 142.1, 145.5, 160.1.
2-Amino-8-[4-bromobenzylidene]-6-methyl-4-(4-bromophenyl)-5,6,7,8-tetrahydrobenzo-4H-
pyran-3-carbonitrile (3m). IR (KBr): vmax = 3453, 3316, 2182, 1668, 1594, 1485, 1413 cm-1.
Anal. calcd. (%) for C24H20Br2N2O: C, 56.25; H, 3.90; N, 5.47; found: C, 56.26; H, 3.78; N,
1
5.58. Major isomer-3n (56%); H NMR (300MHz, CDCl3): δ = 0.89 (d, J = 6.22 Hz, 3H, Me),
1.56-2.24 (m, 4H, 2 CH2), 2.78 (m, 1H, CH), 3.96 (s, 1H, CH), 4.56 (s, 2H, NH2), 6.81 (s, 1H,
Bull. Chem. Soc. Ethiop. 2012, 26(2)

New 2-amino-8-arylidene-4-aryl-5,6,7,8-tetrahydrobenzo-4h-pyran-3-carbonitriles
253
CH=C), 7.21-7.38 (m, 8H, 2 C6H4), 13C NMR (75 MHz, CDCl3): δ = 21.0, 28.8, 35.2, 35.9,
43.5, 60.2, 114.4, 120.0, 122.1, 128.4, 129.0, 129.2, 129.8, 130.5, 132.7, 133.3, 135.3, 141.1,
1
141.5, 158.8. Minor isomer-3n (44%); H NMR (300 MHz, CDCl3): δ = 0.92 (d, J = 6.02 Hz,
3H, Me), 1.56-2.24 (m, 4H, 2 CH2), 2.81 (m, 1H, CH), 3.98 (s, 1H, CH), 4.54 (s, 2H, NH2),
6.81 (s, 1H, CH=C), 7.21-7.38 (m, 8H, 2 C6H4), 13C NMR (75 MHz, CDCl3): δ= 21.0, 28.5,
34.6, 35.0, 42.8, 60.3, 114.5, 120.0, 122.1, 128.4, 128.9, 129.2, 129.6, 130.5, 132.7, 133.2,
135.3, 141.2, 141.6, 158.9.
RESULTS AND DISCUSSION
In a typical experimental procedure, a solution of bisbenzylidenecyclohexanone 1a and
malononitrile 2 in ethanol for synthesis of 2-amino-8-arylidene-4-aryl-5,6,7,8-tetrahydrobenzo-
4H-pyran-3-carbonitrile was heated in the presence of a catalytic amount of DABCO instead of
reported catalysts under reported conditions. Results of reaction with alternative catalyst were
satisfied to the reported methods. The corresponding 4H-pyrans derivatives 3 were obtained in
good to excellent yields. The results are summarized in Table 1.
With the above results in hand, a variety of bisarylidenecyclohexanone at first synthesized
[33] from aromatic aldehydes, possessing both electron-donating and electron-withdrawing
groups. Then these compounds were employed in synthesis of 4H-pyrans formation and in all
the cases, the yields were very good (Scheme 1, Table 1).
Pervious methods for synthesis of 2-amino-8-arylidene-4-aryl-5,6,7,8-tetrahydrobenzo-4H-
pyran-3-carbonitrile suffer from drawbacks such as using of microwave irradiation, long
reaction time, high temperatures and expensive catalyst. All the known products were
1
characterized by comparing their physical and spectral (IR, H NMR and 13C NMR) data with
those of the samples reported in the literature. The data for unknown compounds (Table 1, 3e-
3n) are reported in this paper. As shown in Table 1, bisarylidenecyclohexanones with electron-
withdrawing groups on the aromatic ring led to products with slightly higher yields than
bisarylidenecyclohexanones with electron-donating groups.
Ar
O
*
NH2
CN
*
Ar
cis isomers as one pair enantiomers
trans isomers as one pair enantiomers
Ar
Ar
Ar
Ar
O
NH2
CN
O
NH2
CN
O
NH2
CN
O
*
NH2
CN
+
+
*
Ar
(4S,6S)
Ar
(4R,6R)
Ar
(4R,6S)
Ar
(4S,6R)
Scheme 2. Major and minor product as one pair diasterioisomers.
Bull. Chem. Soc. Ethiop. 2012, 26(2)

254
Gholam Hossein Mahdavinia et al.
Just as seen in the Scheme 2, in the synthesis of new compounds (3h-3n), two stereocenters
are formed thus we expect that the product is mixture of two diastereomers. This subject is
observed in the 1H and 13C NMR spectra obviously so 1H and 13C NMR spectra of these
compounds are specified for two isomers separately.
The possible mechanism for the formation of compound 3 have been as following, initially
using of a acid/base catalytic reaction between DABCO and malononitrile, a carboanion
intermediate 4 has been produced. Then compound 5 was afforded via a Michael adducts of
intermediate to bisarylidenecyclohexanone 1. After that compound 6 as a result of nucleophilic
attack of the OH group on the cyano (CN) moiety take place according to Scheme 3 via
cyclization. Finally through tutomerisation from intermediate 6 products 3 was obtained.
NC
CN
O
Ar
Ar
O
5
Ar
Ar
N
CN
Ar
O
1
Ar
CN
CN
6
DABCO
DABCO
H
4
NH
NH2
CN
CN
Ar
CN
Ar
O
O
CN
2
Ar
Ar
7
3
Scheme 3. A plausible mechanism for the formation of compounds 3.
The method offers several advantages, such as omitting any toxic solvent or catalyst, very
simple work-up procedure without using any chromatographic method, and improving the
yields. Starting materials are inexpensive and commercially available.
ACKNOWLEDGEMENTS
Authors gratefully acknowledge the Teacher Training University and Islamic Azad University-
Marvdasht Branch for supporting of this work.
Bull. Chem. Soc. Ethiop. 2012, 26(2)

New 2-amino-8-arylidene-4-aryl-5,6,7,8-tetrahydrobenzo-4h-pyran-3-carbonitriles
REFERENCES
255
1. Morinaka, Y.; Takahashi, K. Jpn. Patent JP52017498, 1977.
2. Hafez, E.A.A.; Elnagdi, M.H.; Elagamey, A.G.A.; El-Taweel, F.M.A.A. Heterocycles 1987,
26, 903.
3. Li, A.H.; Ji, X.D.; Kim, H.S.; Melman, N.; Jacobson, K.A. Drug Devel. Res. 1999, 48, 171.
4. Urbahns, K.; Horvth, E.; Stasch, J.P.; Mauler, F. Bioorg. Med. Chem. Lett. 2003, 13, 2637.
5. Fravel, B.W. Pyrans and Their Benzo Derivatives: Applications in Comprehensive
Heterocyclic Chemistry III, Katritzky, A.R.; Ramsden, C.A.; Scriven, E.F.V.; Taylor,
R.J.K. (Eds.); Pergamon Press: Oxford; 1995.
6. Dong, Y.; Shi, Q.; Nakagawa-Goto, K.; Wu, P-C.; Morris-Natschke, S.L.; Brossi, A.;
Bastow, K.F.; Lang, J-Y.; Hung, M-C.; Lee, K-H. Bioorg. Med. Chem. 2010, 18, 803.
7. El-Saghier, A.M.M.; Naili, M.B.; Rammash, B.Kh.; Saleh, N.A.; Kreddan, K.M. Arkivoc
2007, 83.
8. Kumar, R.R.; Perumal, S.; Senthilkumar, P.; Yogeeswari, P.; Sriram, D. Bioorg. Med.
Chem. Lett. 2007, 17, 6459.
9. Geen, G.R.; Evans, J.M.; Vong, A.K. Pyrans and Their Benzo Derivatives: Applications in
Comprehensive Heterocyclic Chemistry II, Katritzky, A.R.; Rees, C.W.; Scriven, E.F.V.
(Eds.); Pergamon Press: Oxford; 1995.
10. O´Callaghan, C.N.; McMurry, T.B.H.; O´Brien, J.E. J. Chem. Soc., Perkin Trans. I 1995,
417.
11. Ibrahim, N.S. Heterocycles 1986, 24, 935.
12. Martin, N.; Seoane, C.; Soto, J.L. Tetrahedron 1988, 44, 5861.
13. Heber, D.; Stoyanov, E.V. Synthesis 2003, 227.
14. Balalaie, S.; Sheikh-Ahmadi, M.; Bararjanian, M. Catal. Commun. 2007, 8, 1724.
15. Banerjee, S.; Horn, A.; Khatri, H.; Sereda, G. Tetrahedron Lett. 2011, 52, 1878.
16. Abdel-latif, F.F.; Mashaly, M.M.; Gawish, E.H. J. Chem. Res. 1995, 5, 1220.
17. Singh, K.; Singh, J.; Singh, H. Tetrahedron 1996, 52, 14273.
18. Tu, S.T.; Gao, Y.; Guo, C.; Shi, D.; Lu, Z. Synth. Commun. 2002, 32, 2137.
19. Wang, X.S.; Shi, D.Q.; Tu, S.T.; Yao, C.S. Synth. Commun. 2003, 33, 119.
20. Li, J.T.; Xu, W.Z.; Yang, L.C.; Li, T.S. Synth. Commun. 2004, 34, 4565.
21. Jiu, T.S.; Wang, A.Q.; Wang, X.; Zhang, J.S.; Li, T.S. Synlett 2004, 871.
22. Jiang, Z.Q.; Ji, S.J.; Lu, J.; Yang, J.M. Chin. J. Chem. 2005, 23, 1085.
23. Balalaie, S.; Bararjanian, M.; Amani, A.M.; Movassagh, B. Synlett 2006, 263.
24. Ranu, B.C.; Banerjee, S. Indian J. Chem. Soc. 2008, 47, 1108.
25. Babu, N.S.; Pasha, N.; Rao, V.K.T.; Prasad, S.P.S.; Lingaiah, N. Tetrahedron Lett. 2008,
49, 2730.
26. Yu, L.-Q.; Liu, F.; You, Q.-D. Org. Prep. Proced. Int. 2009, 41, 77.
27. Pore, D.M.; Undale, K.A.; Dongare, B.B.; Desai, U.V. Catal. Lett. 2009, 132, 104.
28. Gurumurthi, S.; Sundari, V.; Valliappan, R. Eur. J. Chem. 2009, 6, 466.
29. Jin, T.-S.; Liu, L.-B.; Zhao, Y.; Li, T.-S. Synth. Commun. 2005, 35, 1859.
30. Zhou, J.-F. Synth. Commun. 2003, 33, 99.
31. Wang, X.-S.; Shi, D.-Q.; Tu, S. J. Chin. J. Chem. 2004, 122.
32. (a) Rostamizadeh, Sh.; Amani, M.A.; Mahdavinia, G.H.; Amiri, G.; Sepehrian, H. Ultrason.
Sonochem. 2010, 17, 306; (b) Rostamizadeh, Sh.; Amani, M.A.; Mahdavinia, G.H.;
Sepehrian, H.; Ebrahimi, S. Synthesis 2010, 1356.
33. Bigdeli, M.A.; Mahdavinia, G.H.; Jafari, S.; Hazarkhani, H. Catal. Commun. 2007, 8, 2228.
Bull. Chem. Soc. Ethiop. 2012, 26(2)